Erotic Lactation between partners or an Adult Nursing Relationship (ANR) may develop from natural breastfeeding of a baby.
Breastfeeding mothers have faced legal ramifications for nursing their children into toddlerhood or in public, or for photographing themselves while nursing.
Researcher Nikki Sullivan, in her book A Critical Introduction to Queer Theory, calls erotic lactation a manifestation of "Queer." She defines Queer as an ideology; that is, as a "sort of vague and indefinable set of practices and (political) positions that has the potential to challenge normative knowledges and identities." Drawing on a statement of David Halperin, she continues "since queer is a positionality rather than an identity in the humanist sense, it is not restricted to gays and lesbians but can be taken up by anyone who feels marginalised as a result of their sexual practices." The heteronormative profile of breastfeeding assumes certain norms: Any kind of sexual activity which includes the woman's milk.
One hypothesis postulates that the breasts grew as a frontal counterpart to the buttocks when primates became upright, thus attracting males, a theory first developed in 1967.
The association of pleasure and nutrition holds true as well for the lips, also erogenous zones, where pleasure may have led to "kiss feeding", in which mothers chew food before passing it on to the child.
Nipple and breast stimulation of women are a near-universal aspect of human sexuality, though nipples in males are not as sexualized.
Humans are the only primates whose females have permanently enlarged breasts after the onset of puberty; the breasts of other primate species are enlarged only during pregnancy and nursing.
In such cases, adult nursing has often caused lactation to continue until it was possible for the child to resume breastfeeding.
Others may want to nurse an adopted child, so use an ANR to stimulate breast milk production before the adoption occurs.
Such activity is widespread, and often unintentional, in the time after a woman gives birth, since many women experience a let-down reflex (releasing milk) when sexually aroused.
The suckling of milk from a female's breast on a regular basis from one or more partner(s).
Some women lose the ability to be aroused while breastfeeding, and thus would not find lactation with a sexual partner to be erotic.